Boring tool



April 28, 1953 c. R. BALLARD BORING TOOL Filed Aug. 16, 194:9v

Patented pr. 28,y 1953 UNITED STATES PA'IENT OFFICE BORING TOOL ClarenceR. Ballard, Dayton, Ohio Application August 16, 1949, Serial No. 110,530

(Cl. T7-2) 11 Claims. 1

This invention relates to boring tools and particularly to tools for theboring or reaming of cylindrical work-pieces, for example, the bushingsor bearings in automotive connecting rods. It has heretofore been thepractice in such work to rigidly mount the bearing or rod in a jig orfixture while a cutter element is driven rotatively and axially throughthe work. It is diicult in the prior art method of boring, therefore, toavoid the formation of a taper in the work, and, moreover, propersetting up of the job requires considerable time and care and the use ofrather extensive equipment. In the latter connection it is frequentlythe practice to utilize centering cones for initial positioning of thework, which cones are then removed before the boring operation is begun.

The object of the invention is to simplify the construction as well asthe means and mode of operation of boring tools as disclosed herein,whereby such tool may not only be economically manufactured but will bemore efficient and accurate in use, adaptable to a wide variety of workpieces, having relatively few parts, and be unlikely to get out ofrepair.

An object of this invention is to simplify the boring of bushings,bearings and the like, While achieving more consistently accurateresults.

Another object of the invention is to avoid belling or the formation oftapers in the work by an improved construction and mode of operationincluding a division of the rotary and axial boring movements betweenthe cutter element and the work.

A further object of the invention is to obtain the accurate positioningof the work made possible by centering cones and to retain such accurateand positive positioning during the boring operation.

Still another object of the invention is to obtain close control overthe boring operation so that the operation can be discontinued and theparts restored to normal position at any time and by a simpleadjustment, as by release of the operators grip upon the tool.

A further object of the invention is to provide a machine possessing theadvantageous structural features, the inherent meritoriouscharacteristics and the mode of operation herein mentioned.

With the above primary and other incidental objects in view as will morefully appear in the specification, the invention intended to beprotected by Letters Patent consists of the features of construction,the parts and combinations thereof, and the mode of operation, ashereinafter described or illustrated in the accompanying drawings, ortheir equivalents.

In carrying out the above objects, there has been evolved a practicalembodiment of the inventon wherein a boring tool comprises a rotatableshaft, a pair of opposed centering cones keyed to the shaft andpositioning between them a cylindrical work piece in concentric relationto the shaft, a sleeve in loosely surroundingrelation to the shaft andabutting one of the centering cones, the other being backed up by a coilspring, screw threads on the shaft, a hand operated plunger carried bythe sleeve to engage the screw threads on the shaft and so induce anaxial motion of the sleeve, cones and work piece as an assembly againstthe urging of the coil spring in response to rotation of the shaft, anda cutter element carried by the shaft for rotation in a fixed plane andprojecting into cooperative relation with the internal surface of thework piece.

Referring Vto the accompanying drawing, wherein is found the preferredbut obviously not necessarily the only form of embodiment of theinvention,

Fig. 1 is a view in side elevation of a tool in accordance with theinstant invention, showing a means for driving the tool and furthershowing a connecting rod being held for action of the tool thereupon;

Fig. 2 is an enlarged view similar to Fig. 1 with the connecting rodremoved except for a diagrammatic indication thereof;

Fig. 3 is an exploded view in side elevation of parts ofthe tool;

Fig. 4 is a fragmentary View of the shaft; and

Fig. 5 is a perspective view of one of the centering cones.

Like parts are indicated by similar characters of reference throughoutthe several views.

Referring to the drawing, according to the illustrative embodiment ofthe invention the boring tool comprises a rotatable shaft l 0 having aSquared formation at its right hand or inner end to be received in achuck, as the chuck II shown in Fig. 1 as a part of a power tool i2. Theleft hand or outer end of the shaft is free and unsupported. Extendingfrom the outer end of the shaft over approximately two-thirds the lengththereof is a peripheral screw thread i3. A transverse opening or bore I4in the shaft receives a cutter element I5 positioned and securedrelatively to the shaft by axial and lateral set screws I6 and Il. Thecutting edge of the element I5 protrudes a distance above the peripheryof shaft I determined by the setting of screw I6, While screw l1 locksthe cutter element in its desired position of adjustment. The bore I4 iscut angularly in the shaft lil so as to present a smooth shaft surfacediametrically opposite the cutting edge facilitating micrometermeasurements of the height of the cutting edge.

In the periphery of the shaft it is a longitudinal keyway i8, beginning`zit-fthe. outer e'nd of the shaft and terminating adjacent the inner endthereof. Mounted upon the shaft and formed with a key i9 received in theslot i8 vis a first centering cone 2B facing the outer end of the shaft.Similarly mounted upon and keyed to the shaft I is a second centeringcone El oppositely disposed with respeotto the nrst cone 20 and lyingbetween the first cone and the outer end of the shaft.

The cone 2d is resiliently seated upon a coil spring.l ,22'surrounding'. the shaft lll and based on aoisc. 23A pinned to .theinner end of the shaft. Cone El is formed. with a rearwardly projectingextension 2li of reduced diameter having thereinan. annular groove 2r?.

The extension 24de .seated in a recess 2S in the. .end oi a sleeve 2l,the groove i5 receiving lateral dovvel pins 22. to. connect sleeve 2land cone 2| forunitary longitudinal movement while permitting relativerotary movement. The sleeve 2l' loosely surmounts the outer end of theshaft IB and has a lateral opening 29 therein through which a plunger 3ly enter the interior of the sleeve and engage screw thread I3. Theplunger 3i is pivotally carried on the inner end of a lever 32 pivotallymounted at its outer end to the exterior of the sleeve 2l. A spring 33urges the lever Si. upward or in a direction. to Withdraw plunger (ilfrom screw thread E3, the plunger being thus normally disengaged fromthe screw thread.

As indicated in Figs. l and 2, the centering cones 2Q and 2i arevconstructed and arrange. t0 enter and engage the opposite ends of acylindrical work piece 34, holding the work pie-ce in concentricrelation to the shaft it. The springr 22 normally positions the assemblycomprising cone 2U, work piece Sti, cone 2l and sleeve 2'! in suchrelation to the cutter element 'i5 as to place the element in inwardlyadjacent relation to the work piece Sil, the construction andarrangement being such that the cutter element may work upon theyinternal surface of the work piece inresponse to relative axial androtative movements between the element and work piece.

The cones 22 and 2i are formed with mating slots 35 and' 38 defining avpassageway through which the cutter element travels there-by allow inga complete traverse "of theH workpiece by the cutter. The relativerotary` motion between the cutter and work piece is obtained lbyfixedlymounting-thecutter elementen therotary shaft IE), the cutterr rotating.therewithl 'in a fined transverse plane 'with respect to theshaft.Longitudinal motion .off the: cntterf relative to the work pieoeisaccomplished through a shifting of the centeringf cones 2li. and". 2l,suoni-novement :being-produced by: engagement of the plunger. ,3i in thescrewuthread i3' to. induce an axialtravel of @sleeve 2l and cone 2itoward' theinner end .of the shaft response to' rotation of the-shaft.

A. particular. ap ploationy of. the boring tool, but notits only. use,iszin the reooringor reamingY ofy connecting rods, such4 a'fdevice.replocnt-y ing the work piece 34 in Fig. 1 and there shown as beingacted upon by the tool. In the use of the tool, the sleeve assemblycomprising cone 2l, sleeve 27, plunger 3l and lever 32 is removed fromshaft l0 and the connecting rod or other piece to be bored, slipped onthe 'shaft and brought into engagement with the cone 2t. The sleeveassembly then is remounted on the shaft in following relation to thework piece, the cone 2! being moved to engage'the work piece inconjunction *with cone 2U substantially as shown in Fig. 2. While theconnecting rod is held as shown in Fig. 1 to inhibit rotation thereofwith the centering cones, rotary motion of the shaft fchuclr Il.

lll is initiated through the power tool i2 and The sleeve 2i and lever32 are designed to be grasped in the hand of an operator, who, lafterrotation of shaft lil is initiated, compresses lever 32 upon sleeve 2lto engage plunger 3l in the screw thread i3. rThereupon continued rotarymotion of the. shaft produces .an axial movement of sleeve 2l and .cone2S to initially eiect a firm. clamping engagement posie toning. .of theworlr piece. 3flbetween thecones 20 and. 2l. Continued axial movement ofthe sleeve assembly .causes the work. piece and cone 2li to moveinwardly along the shaft against the resilient resistance of spring 22which is oompressed by such motion. The work piece 3ft is thereby causedto traverse the rotating cutter element l5, the combination of rotaryand axial movements serving to bore or ream the work piece in thedesired manner.

' The cutting action is under the close control of the operator who caninterrupt such. action at any time by releasing his grip on lever 32.Upon release of the lever 32, the plunger 3i is withdrawn by spring 33from engagement with screw thread i3. Movement of the sleeve and coneassembly inwardly alongthe shaft is accordingly discontinued, the partsbeing restored to normal starting position as shown in Fig. 2, underinfluence of spring. 22.

From the above description it will be apparent that there'is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modiiicationin its forni, proportions,detail construction and arrangement of parts without departing fromtheprinciple involved or sacrificing any .of its advantages.

While in order to com-ply with the statutelthe invention has beendescribed in language more or less specific as to structural features,itgis. to be understood that the invention is not limited to 'thespecific' features shown,v but that the means and construction hereindisclosed comprise but one 'of several modes of putting the inventioninto effect.

Having thus described my invention, I claim:

1.'1n a boring tool having a rotatable shaft, opposed centering conesmounted on said-shaft for'rotary motion therewith and for axial motionrelative thereto, said cones being arranged to engage and position an.intermediate cylindrical Work piece in concentric relationto said shaft,a cutter element carried by saidshaft and engageablewith the internalsurface of the work piece, and means. for moving said centering conesaxially to shift the work piece relatively to the cutter element.

2. In a boring tool having a rotatable shaft, means for holding.acylindrical work piece in concentric relation tot said shaft, acutterfelement carried by said shaft and enga-geabley with the in,

ternal surface of said work piece, and means for moving said holdingmeans axially of the shaft to shift the work piece in a longitudinaldirection relative to the cutter element.

3. A boring tool, including a cutter element rotatable in a fixed plane,longitudinally shiftable means for holding a cylindrical work piece inconcentric relation to said cutter element, and means for simultaneouslyeffecting rotation of said cutter element and longitudinal shiftingmotion of said holding means relative thereto.

4. A boring tool, including a rotatable shaft, means for holding acylindrical work piece in concentric relation to said shaft, a cutterelement carried by said shaft and engageable with the internal surfaceof said work piece, and means selectively responsive to rotation of saidshaft for moving said holding means axially of the shaft inaccompaniment with rotation of said cutter element.

5. A boring tool, including a rotatable shaft, means for holding acylindrical work piece in concentric relation to said shaft, a cutterelement carried by said shaft and engageable with the internal surfaceof said work piece, a sleeve in loosely surrounding relation to saidshaft and abutting said holding means, screw threads on said shaftunderlying said sleeve, and means carried by said sleeve selectivelyengageable with said screw threads to effect an axial movement of saidsleeve and holding means in response to rotation of said shaft.

6. A boring tool, including a rotatable shaft, opposed centering conesmounted on said shaft for rotary motion therewith and for axial motionrelative thereto, said cones being arranged to engage and position anintermediate cylindrical work piece in concentric relation to saidshaft, a cutter element carried by said shaft and engageable with theinternal surface of the work piece, and means responsive to rotation ofsaid shaft to move said centering cones axially of said shaft to shiftthe work piece relative to the cutter element.

7. A boring tool, including a rotatable shaft, opposed centering conesmounted on said shaft for rotary motion therewith and for axial motionrelative thereto, said cones being arranged to engage and position acylindrical Work piece in concentric relation to said shaft, a cutterelement transversely mounted in said shaft to protrude a short distanceabove the periphery thereof, mating longitudinal slots in said conesdefining a passage for the relative longitudinal movement of said cutterelement and said cones, means responsive to rotation of said shaft toshift said cones axially of said shaft to carry the work piecelongitudinally thereof in accompaniment with rotation of the cutterelement, and spring means for initially positioning said centering conesand to provide a force for return axial motion thereof.

8. A boring tool, including a rotatable shaft, opposed centering coneskeyed to said shaft and arranged to engage and position an intermediatecylindrical work piece in concentric relation to said shaft, a coilspring providing a resilient seat for one of said cones, a sleeveloosely mounted on said shaft and abutting the other of said cones,longitudinal motion of said sleeve serving to shift the assemblycomprising the cones and work piece axially of the shaft against theresilient resistance of said spring, selectively operable means forproducing progressive longitudinal motion of said sleeve in response torotation of said shaft, and a cutter element carried by said shaft toprotrude radially into cooperative relation with the internal surface ofthe work piece.

9. A boring tool according to claim 8, characterized in that saidselectively operable means includes a screw threaded periphery on saidshaft and a plunger mounted in said sleeve for radial motion intoengagement with said screw threaded periphery.

10. A boring tool including a rotatable shaft presenting a squared innerend for cooperation with rotary driving means and further presenting ascrew threaded periphery extending from the outer end over a part of thelength thereof, a first centering cone keyed to said shaft and facingsaid outer end, said cone providing a seat for a cylindrical work pieceslipped over the outer end of said shaft, a coil spring backing for saidfirst cone, a sleeve assembly slipped over the outer end of said shaftin following relation to the work piece and including a second conefacing the first and keyed to said shaft and further including a sleeveloosely surmounting said shaft and connected to said second cone forunitary longitudinal and relative rotational motions, a plunger radiallymounted in said sleeve to be manually pressed into cooperativeengagement with the screw threaded periphery of said shaft wherebyrotary motion of said shaft produces an axial travel of said sleeveassembly toward said first cone to clamp the work piece between saidcones in concentric relation to said shaft, continued travel serving toadvance said cones and the work piece as a unit toward the inner end ofsaid shaft, and a cutter element carried by said shaft for rotationtherewith and protruding radially for cooperative engagement with theinternal surface of the work piece.

11. A boring tool according to claim 10, characterized by mating slotsin said irst and second cones defining a longitudinal passageway intowhich said cutter element projects.

CLARENCE R. BALLARD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,376,451 Martell May 3, 1921 1,521,751 Campbell Jan. 6, 19252,091,628 Carlson Aug. 31, 1937 2,252,121 Fuglie Aug. 12, 1941 FOREIGNPATENTS Number Country Date 310,188 Great Britain Apr. 25, 1929

